CAPE CANAVERAL, Florida (Reuters) - NASA chief Charles Bolden has advice on how to handle a large asteroid headed toward New York City: Pray. That's about all the United States - or anyone for that matter - could do at this point about unknown asteroids and meteors that may be on a collision course with Earth, Bolden told lawmakers at a U.S. House of Representatives Science Committee hearing on Tuesday. An asteroid estimated to be have been about 55 feet in diameter exploded on February 15 over Chelyabinsk, Russia, generating shock waves that shattered windows and damaged buildings. More than...